This invention relates to thermal management of personal computers, and, more particularly, to thermal management of desktop and notebook computers.
Conventional thermal management of personal computers generally involves the use of a single thermistor physically attached to a xe2x80x9cworst casexe2x80x9d location in the computer. When the temperature passes fixed temperature trip-points, the management system initiates a fixed response such as turning on or off a fan.
The thermal profile of a computer depends on its electrical and mechanical setup. The actual location of a hot spot will change as the configuration of the computer changes. For example, a computer can run hotter in a section depending upon whether AC or battery power is used as the power source.
While multiple thermistors can be used to monitor all possible hot spots of a computer, this greatly complicates the circuitry. This invention addresses compensating for multiple, characterized configurations by polling the system for indirect causes of temperature profile changes. The thermal management system takes into account not only direct thermal readings but other indirect measures of the thermal condition of the computer, for example, whether the computer is under AC or battery power, to optimally respond to a rise in temperature inside a computer, allowing the response to be customized to the operating condition of the computer.
In general, the invention relates to a method of thermal management of a computer. The method features determining a temperature of a predetermined location in the computer, reading at least one indirect input of the computer, and determining a desired state of at least one cooling option, for example, a fan, based on the determined temperature and the indirect input.
In particular embodiments of the invention, the method includes placing cooling options in desired states. To determine the desired states of the cooling options, an index is formed based on the indirect inputs and the index indicates to which of a plurality of tables of desired states of the cooling options to refer. The tables include temperature ranges for the determined temperature, and the desired states of the cooling options in each table are dependent on the temperature ranges.
In one preferred illustrated embodiment, the step of determining the desired states of the cooling options features adjusting the value of the temperature input based on the indirect inputs; the desired states of the cooling options are dependent on the adjusted value of the temperature.
The indirect inputs include whether the computer is under AC or battery power, whether the computer is docked to a docking station, whether a display screen is closed, whether an option card is installed, whether a device is present which requires lower ambient temperature or generates disproportionate heat, whether an audio function is running, which processor is installed in the computer, a user-setable bit that can customize cooling requirements, a status of a charge of a battery, a video mode of the computer, whether a video monitor is being used, whether there has been a sudden and drastic increase in temperature, whether a hard drive or a floppy drive is being spun up or accessed, whether a battery is being charged, and whether the computer is in a power conservation mode.
The cooling options include a fan, a frequency setting of a processor, a complete or partial standby condition of the processor, a time-out of a peripheral, a frequency setting of a peripheral, and turning off the computer.
According to another aspect of the invention, an apparatus for thermal management of a computer includes a processor, a device for measuring temperature, an output from the device being communicated to the processor, at least one cooling option, an output from the processor controlling the at least one cooling option, and at least one indirect input related to a mode of the computer being communicated to the processor, the at least one indirect input affecting the output from the processor to the cooling resource.
Advantages of the thermal management system include the ability to use multiple cooling options and to adjust the order of implementing the cooling options depending upon the operating condition of the computer. For example, since the fan itself requires a significant amount of power, it can be advantageous to slow down the CPU before activating the fan while on battery power, but request full CPU power with the fan activated while under AC power. Additionally, the system accurately monitors the thermal profile of the computer enabling the advantageous implementation of cooling options even when the xe2x80x9cworst casexe2x80x9d location in the computer is within acceptable temperature limits.